(1) Technical Field
The subject invention relates to a device for vertically supporting a tree. More specifically, the subject invention relates to a tree stand having an improved rib construction.
(2) Background Art
Tree stands are commonly used for supporting trees, e.g., Christmas trees, in a vertically upright manner. Such tree stands usually include a receptacle for receiving the base, or trunk, of a tree along with a volume of water, and some type of bracing means, e.g., thumb screws, straps, etc. for propping the tree in a vertically upright posture. The water contained in the receptacle surrounds the tree base and provides nourishment to the tree thereby prolonging its live appearance.
One such tree stand is shown in U.S. Pat. No. 4,884,363 to Sofy issued Dec. 5, 1989. The assembly generally comprises a tree stand including a cup shaped receptacle including an upwardly extending peripheral wall, a skirt disposed about the exterior of the receptacle, and a base extending outwardly and downwardly from the skirt. The base extends from the skirt at a relatively greater angle with respect to the longitudinal axis than the angle formed by the skirt and the longitudinal axis. The base comprises a first annular surface that extends from the periphery of the skirt. The base further comprises a second surface having the shape of an inverted frustum which extends from the outermost edge of the first surface. A leg extends downwardly from the second surface. With this construction, large forces imparted to the base can tend to buckle the base or cause it to fall over if the force of the tree is too great for the base to support. Although not shown in the patent, a later developed embodiment included four ribs spaced in 90 degree increments. The ribs are disposed on the bottom side of the device and extend between the leg and the second surface. One deficiency that may still arise with this type of stand is that excessive forces such as by large trees may still tend to buckle the first surface because of the relatively large angle between the first surface and the longitudinal axis.
Tree stands are also known which have skirts comprising a peripheral wall extending at a constant slope or angle from the outer surface of a receptacle to the ground. These include U.S. Pat. No. 4,571,881 to Lathim issued Feb. 25, 1986, U.S. Pat. No. 2,980,377 to Nielsen et al., issued Apr. 18, 1961 and U.S. Pat. No. 2,493,633 to Mart issued Jan. 3, 1950. Because the skirt of the devices shown in each of these patents extends at a relatively small angle relative to the longitudinal axis, the forces (particularly the vertical component) tending to buckle the skirt are more readily supported by the skirt wall. It is, however, known to add strengthening elements as shown in the '377 and '633 patents above.
Other patents showing tree stands having strengthening elements for added stability are U.S. Pat. No. 4,126,963 to Dunbar issued Nov. 28, 1978 and U.S. Pat. No. 2,337,914 to Meldrum issued Dec. 28, 1943.
Although these patents show strengthening elements having various configurations, none of them disclose a rib construction that could be used to strengthen a base assembly extending from a skirt at a greater angle relative to the longitudinal axis of the stand than the skirt.